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I haven't used my Mesa simulclass 2: Ninety power amp in probably two years. When I went to turn it on today, the amp turned on, but the tubes never lit up and I couldn't get a signal. .I had the amp stored in a SKB case where it was dry and cool...

Does anyone know what could be possibly wrong with it? Did the non-use of the tubes have anything to do with the problem?

I am going to try and sell it, but I fear that if I take it to an amp tech the cost of repairs may nullify anything I could get for it... :(

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dementedchord Fri, 08/24/2007 - 11:32

no glow means no heater voltage...and perhaps the rest as well... start with the fuses... make sure it's on a load when you power it up too... non use is a non issue unless we're talkin a decade maybe then somw caps could be suspect but that's most likely not your problem... check that power cord too... unlikely but... it's the silly stuff that bites ya on the ass...

moonbaby Fri, 08/24/2007 - 13:24

You did have a speaker load connected to it, correct ? By "no signal", you meant "no sound", right"? "No load" means no speaker to load the amp's output, BTW. Demento is right on about a fuse being blown. This can happen upon initial power-up if the amp has sat around that long without being used. Some fuses are internal, some are on the rear of the amp. Mesa puts fuses in different places on different models of their gear. You might consult the owners' manual, or contact their tech support dept. on those details.

moonbaby Mon, 09/17/2007 - 22:07

JesterMasque wrote: If the fuse was blown there would be no power-up on a Mesa power amp. I do not know about others...

Better re-read the posts, Vinnie. There are SEVERAL fuses inside Mesa amps (and many others, I DO know) to protect specific portions of the circuitry to not self-destruct. Just because a fuse blows does not mean the entire amp shuts down.
Addendum: The schematic for that particular amp shows a "1-amp Fast-blo" fuse on each channels' power tube circuit. This may definitely be the culprit. This is in addition to the "Mains Slo-Blo" power fuse that is user-accessible.

moonbaby Wed, 09/19/2007 - 07:21

Understandable. IMHO, tube amps have gotten way too sophisticated these days. Sometimes for the better, sometimes not. Mesa is a prime example of this. Their gear is designed to not as easily fail in a catastrophic way, compared to, say a Marshall Super Lead from the 70s, could. But things like flawed printed circuit boards, extra relays, and exotic ICs have contributed to modern amps' intermittencies and headaches.
BTW, Vinnie, did you ever get to the problem with your Madison cab?

JesterMasque Fri, 09/21/2007 - 09:39

Not yet... I have been waiting for dad to get around to looking at it with me. I think I will just bring it to my local guy because I just replaced all of my tubes and I want to use them damnit, haha!

So I am pissed... Not really, but check this out. My friend just found a 1998 Mesa 2:50 like mine, but for (get this) $450! I paid $1,000 for mine four years ago! The thing sounds amazing and the wiring all looks clean so I am really happy for him.